TV REVIEW No, nothing to do with Billy Joel...

THE ONE WHERE: When Oliver investigates the case of an innocent man facing the death sentence he exposes corruption at the heart of a chemical company. And then a rescue mission into a prison leads to his secret identity being compromised…

THE VERDICT: A strong, engaging episode of Arrow , one that targets the heart of what makes Oliver’s brand of vigilantilism so troubling. Diggle calls him out directly: “Oliver, you’re not a soldier – you’re a criminal. And a murderer.” Later on Laurel brands him “a killer” – “He would have killed that man. I looked in his eyes. It’s like he had no remorse.” It feels like the beginning of an powerful ethical arc for the character, and while he pulls the man he’s interrogating from the path of an oncoming train there’s a part of you utterly convinced he’ll leave him to become track-jam. Elsewhere the show’s mythos continues to slot into place, with Diggle accepting the inevitable Alfred gig (lovely, amusing character beat between the two bodyguards when they realise Oliver’s slipped away again). The show’s debt to Christopher Nolan has never been more obvious than in this episode – as an attorney given to nocturnal rooftop meetings with a masked vigilante Laurel’s clearly fulfilling the role of Rachel Dawes, while Oliver definitely seems to have pilfered the Dark Knight’s voice-changing tech. It’s an episode that hooks us with some genuinely compelling questions, too – what is Tempest? Why is the wreck of the boat in the warehouse? And, most crucially and cliff-hangerish of all, how will Oliver survive the exposure of his secret identity? It feels like the show is gathering some real narrative momentum. John Barrowman’s guest-shot is a little underwhelming, mind. “Mysterious Man In Back Of Limo” seems exactly what we all expected. Me, I was hoping he’d be the Electrocutioner…

HMM: Would Oliver really be so sloppy as to expose his face to the prison’s security cam? It’s the kind of amateur hour cock-up that could seriously compromise your JLA membership. Rookie error? Or part of some cunning double-bluff yet to be revealed?

DID YOU SPOT?: More subtle references to corners of the DC Universe. The city of Bludhaven is adjacent to Gotham and was home turf to Nightwing for a while. Iron Heights is Central City’s high-security prison, more usually seen in the pages of The Flash . And, of course, Big Belly Burger is the fast food emporium of choice in the DCU, seemingly untouched by health-minded rebranding. Does Superman supersize?

BEST LINE: Diggle: “You were born with a platinum spoon in your mouth, Queen. What, you spend five years on an island with no room service and suddenly you found religion?”